The present invention relates to a system for reusing a thermal energy of an air discharged from a heated air source to heat a combustion air to be supplied into a combustion device so that the combustion air is mixed with a fuel to be used for combustion in the combustion device.
JP-A-9-236201 discloses that a pressurized atmospheric air is mixed with an air discharged from a heated air source, and the mixture of the pressurized atmospheric air and the air discharged from the heated air source is supplied into a combustor. JP-A-10-196933 discloses that the air discharged from the heated air source is pressurized to be supplied into the combustor.
An object of the present invention is to provide a system for reusing a thermal energy of an air discharged from a heated air source to heat a combustion air to be supplied into a combustion device so that the combustion air is mixed with a fuel to generate a high-temperature combustion gas by combusting the fuel with the combustion air in the combustion device, in which system, an air feeder for feeding the combustion air toward the combustion device is restrained from being damaged by the thermal energy of the air discharged from the heated air source, and/or the air can be effectively discharged from the heated air source even when a difference between an internal gaseous pressure in the heated air source and the atmospheric pressure is small.
In a system for reusing a thermal energy of an air discharged from a heated air source to heat a combustion air to be supplied into a combustion device so that the combustion air is mixed with a fuel to generate a high-temperature combustion gas by combusting the fuel with the combustion air in the combustion device, comprising, an air feeder for sucking the combustion air and urging the combustion air toward the combustion device, and an inlet passage arranged at an upstream side of the air feeder to allow the combustion air to flow toward the air feeder.
Since the inlet passage includes a first inlet port connected fluidly to the heated air source to take the air from the heated air source through the first inlet port into the inlet passage and a second inlet port connected fluidly to the atmosphere to take an atmospheric air from the atmosphere through the second inlet port into the inlet passage so that both the atmospheric air and the air discharged from the heated air source are incorporated to the combustion air to be fed into the combustion device through the air feeder, a temperature and pressure in the inlet passage arranged at the upstream side of the air feeder are kept small so that the air feeder is restrained from being damaged by the thermal energy of the air discharged from the heated air source, and/or the air can be effectively discharged from the heated air source even when a difference between an internal gaseous pressure in the heated air source and the atmospheric pressure is small.
When the air feeder is capable of making a gaseous pressure at the second inlet port less than the atmospheric pressure, the air can be more effectively discharged from the heated air source to the inlet passage even when the internal gaseous pressure in the heated air source is significantly small, and the atmospheric air can be more effectively taken to the inlet passage from the atmosphere.
The first inlet port may include a variable throttle for adjusting an opening area of the first inlet port, so that the air discharged from the heated air source is retrained or prevented from flowing into the inlet passage toward the air feeder, and/or a concentration or mass-flow-rate of oxygen in the combustion air is adjusted by changing a flow rate of the air discharged from the heated air source into the inlet passage. In this case, it is preferable for restraining an excessive heat of the inlet passage, particularly when the air discharged from the heated air source is substantially prevented from flowing through the inlet passage toward the air feeder, that the inlet passage further includes a third inlet port arranged at an upstream side of the variable throttle and opening to the atmosphere to allow the air from the heated air source to be discharged through the third inlet port to the atmosphere.
The second inlet port may include a variable throttle for adjusting an opening area of the second inlet port so that the atmospheric air is retrained from flowing into the inlet passage toward the air feeder and/or the concentration or mass-flow-rate of oxygen in the combustion air is adjusted by changing a flow rate of the atmospheric air flowing into the inlet passage.
The inlet passage may include a variable throttle for adjusting an opening area of the inlet passage to change a flow rate of the combustion air through the air feeder so that a fuel-air ratio in the combustion device is adjusted. In this case, it is preferable for correctly controlling a ratio between the fuel and the mass-flow-rate of oxygen for the combustion and restraining the variable throttle from being damaged by the thermal energy of the air discharged from the heated air source that the third variable throttle is arranged at a downstream side of he second inlet port.
The heated air source may include at least one of a gas turbine, a combustor and a combustion engine. The combustion device may include at least one of a gas turbine, a combustor and a combustion engine. The combustion device may include a combustor for combusting therein the fuel with the combustion air, a first heat exchanger for heating a fluid by a heat energy of the combustion gas, and a second heat exchanger for heating a water by the heated fluid.
When the air feeder is capable of making a gaseous pressure at a position at which the air and the atmospheric air join less than the atmospheric pressure, both the air and the atmospheric air can be effectively taken into the inlet passage and be effectively mixed or agitated with each other.
When a bypass passage includes an inlet port opening to the inlet passage at a downstream side of the first inlet port and at an upstream side of the second inlet port to allow at least a part of the air to flow into the bypass passage while the atmospheric air is restrained from flowing into the bypass passage, and an outlet port for allowing the at least a part of the air therethrough to be joined with the combustion gas after the combustion gas is generated by combusting the fuel with the combustion air supplied through the air feeder, that is, at a downstream side of a combusting position at which the fuel and the combustion air join to combust the fuel with the combustion air, a flow rate of the air discharged from the heated air source, a thermal energy of which air is utilized, is increased while the fuel-air ratio or the concentration or mass-flow-rate of oxygen in the combustion air is correctly adjusted, so that a part of the thermal energy of the air discharged from the heated air source to be discharged to the atmosphere is decreased.
If the air feeder is operable to feed the atmospheric air from the second inlet port into the combustion device when the air discharged from the heated air source flows into the inlet passage and the fuel is prevented from being combusted with the combustion air in the combustion device, an excessive heat and/or dew condensation in the inlet passage, the air feeder or the combustion device is restrained by the atmospheric air.
It is preferable for restraining the excessive heat and/or dew condensation in the inlet passage, the air feeder or the combustion device that the second variable throttle is openable to take the atmospheric air into the inlet passage when the air is taken from the heated air source through the first inlet port into the inlet passage.